Transistor Power Converter Degradation Detection via Turn-off Energy
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Solution Overview
Problem
Existing methods for monitoring the operating conditions of transistor-based power converters are inadequate in detecting early signs of degradation and potential failures, particularly due to thermal and electrical stresses, leading to high failure rates in mission-critical applications.
Innovation Solution
An operating condition monitor that measures turn-off transient energy by combining current and voltage sensors with a processor to compare measurements to a threshold, issuing an event signal for degradation detection, allowing for improved health monitoring and remaining useful life estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing monitoring techniques are used to detect power device degradation, then failure detection is possible at final stage, but early stage degradation cannot be detected and custom modification of components is required
Solution Approach 1:
The power device itself generates the measurement signal (turn-off transient energy) through its normal switching operation. The degradation of the device directly affects this naturally occurring signal, eliminating the need for external modification or separate sensing components. The device monitors its own health through parameters inherent to its operation.
Solution Approach 2:
The turn-off transient energy serves as an intermediary parameter that indirectly reflects the physical degradation state of bond wires and solder joints. Instead of directly measuring physical dimensions or material properties, the system measures the energy characteristic that changes as degradation progresses, providing early warning before catastrophic failure.
2Reliability
If on-state voltage monitoring is used to detect power device ageing, then degradation can be identified, but signal noise and switching disturbances cause false identifications
Solution Approach 1:
The monitoring approach shifts from measuring on-state voltage to measuring turn-off transient energy. This parameter change exploits the fact that degradation affects the turn-off switching characteristics more significantly than steady-state operation, and the transient nature of the measurement provides a cleaner signal that is less susceptible to ongoing switching disturbances and noise.
3Reliability
If thermal resistance based techniques are used to monitor solder fatigue, then degradation can be monitored, but junction temperature measurement is challenging and not directly measurable
Solution Approach 1:
The system replaces direct thermal measurement (which would require physical temperature sensors at the junction) with an electrical measurement approach. By measuring turn-off transient energy, which is influenced by thermal conditions and degradation, the system indirectly monitors solder fatigue without requiring direct thermal sensing, thus avoiding the measurement difficulties associated with junction temperature.
Data Source
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AI summary
An operating condition monitor (100) for monitoring an operating condition of a transistor-based power converter (102), comprising: a sensing apparatus (106) configured to measure a turn-off transient energy of the power converter (102), a processor (108) in communication with the sensing apparatus (106) to receive the measurement of the turn-off transient energy, the processor being configured to: compare the measurement of the turn-off transient energy to a threshold; and issue an event signal based on the comparison to the threshold meeting a comparison criterion. A method (200, 200') of monitoring an operating state of a transistor-based power converter is also disclosed.